Question

Exercise 1Pulse rates were measured on a random sample of 25 distance runners. The dataresulted in an average pulse rate of ̄x= 58.2 beats per minute with a standarddeviation ofs= 8.5.

(a) Find a 95% confidence interval for the mean pulse rate for the population ofdistance runners.

(b) Interpret the interval in words.

Answer 1

SolutionA:

95% confidence interval for the mean pulse rate for the population ofdistance runners.

xbar-tc*s/sqrt(n),xbar+tc*s/sqrt(n)

t criticla for 0.025 alpha and 24 df is

=T.INV(0.025;24)

=2.0639

therefore

58.2-2.0639*8.5/sqrt(25),58.22.0639*8.5/sqrt(25

54.69137,61.70863

lower limit=54.69137

upper limit=61.70863

(b) Interpret the interval in words.

we are 95% confident that the true mean pulse rate for the population ofdistance runners lies in between 54.69137 and 61.70863